Refrigeration evaporator



March 12, 1935. J. D. LEAR REFRIGERATION EVAPORATOR Filed Jan. 4, 1933 2 Sheets-Sheet 1 Zmoentor March 12, 1935. J. D. LEAR REFRIGERATION EVAPORATOR 2 Sheets-Sheet 2 Filed Jan. 4, 1953 atented Mar. 12, E935;

UNITED STATES PATENT OFFICE REFRIGERATION EVAPORATOR Joseph D. Lear, Buffalo, N. Y., assignor to Fedders Manufacturing Company, Inc., Buflalo,

This invention relates to refrigeration, and it has particular reference to evaporators adapted for use in flooded systems of evaporation.

The invention contemplates an improved flood- 5 ed type evaporator where the ratio of the refrigerant volume to the evaporative surface area is maintained at a minimum to obtain improvement in both space economy and thermal efliciency.

In prior devices, particularly of the pressed or cast double wall type, this desideratum has been approached by introducing refrigerant between spaced walls. Such devices, however, have proved either too costly or are otherwise impractical. In pressed sheet metal apparatus, for example, the die and welding or soldering costs for a reinforced sheet metal structure have been found to be prohibitive in a number of cases, while in other types the wall thiclmess required to prevent porosity and provide the needed strength has generally prohibited their use.

In addition to the above, the headers or float chambers of these prior devices have occupied a space not commensurate with their heat transference efficiency, since they were constructed to house a ball float and an accordingly large volume of inactive refrigerant. Inasmuch as the flooded system, as exemplified by these devices, has necessarily carried more refrigerant and occupied more space than a comparative device in the dry system, the latter has recently prevailed in the industry, although not generally conceded to be the most desirable for other operating reasons.

In the present invention, an evaporator is provided which occupies a minimum of space in a refrigerator and yet is devised to present at least as much refrigerative surface as prior structures. In addition to this, its general shape is such as to encourage air circulation thereabout in the most eflicient manner.

The present evaporator is constructed of two major parts which may be connected by a single soldered joint, to form a. float chamber, refrigerating surface, and a freezing chamber. These parts are formed as telescoped cylindrical cup shaped shells, and are thus of the simplest form for die or casting operations. The major evaporative surface consists of a pair of closely spaced circular walls providing an eflicient shape both to resist pressures and to encourage proper air circulation thereabout. The interior wall of the structure cooperates to form a chamber for receiving ice trays, and, since it is in direct and continuous contact with the refrigerant, it forms an effective sharp freezing chamber. The space between the rear wall of the freezing chamber and that of the outer shell is utilized to provide an integral float chamber to house a float of the open bucket type. This float is specially devised for diametral pivotal movement and its 5 shape and proportions are such asto occupy a major portion of the refrigerant space in this chamber.

Other features of the invention reside in the provision of means for adjusting the liquid level in the device andin various structural relationships more fully set forth in the accompanying specification and drawings, wherein:

Fig. 1 is a diagrammatic front view of a domestic refrigerator containing the evaporator of the present invention;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a section on the line 4-4 of Fig. 2;

Fig. 5 is a section on the line 5-5 of Fig. 4.

Referring to the drawings, the evaporator is formed of an outer shell 10 having a cylindrical wall 11 and a rear wall 12, and a similar inner shell 13 having a cylindrical wall 14 of less diameter than the wall 11 of the outer shell, and a rear wall 15. The length of the shell 10 is greater than that of the shell 13, so that when the shell 13 is telescoped within the outer shell 10, its rear wall 15 is spaced from the rear wall 12 to form a substantially disc shaped float chamber 16 therebetween. When thus assembled, the space between the cylindrical portions of the shells is preferably restricted to a degree hereinafter described to provide a major evaporation chamber 17 communicating with the float cham- 35 her 16. The space within the inner shell 13 forms an enlarged sharp freezing chamber 18, which in comparison with the overall volume of the entire device, occupies a major portion of such volume.

It has been found particularly advantageous 40 to draw the shells out of a suitable blank to the shapes disclosed, as this type of die operation provides the most advantageous grain structure for resisting the tension and compression forces within the evaporation space. The rear ends of 45 the shells are maintained in concentricity by the provision of a plurality of radially spaced beads 19 formed out of the inner shell 13 and frictionally engaging the inner wall of the outer shell 10. The outer end of the inner shell 13 is provided with an annular flared portion 21 which engages the wall of the outer shell 10 and which is overlapped by an inturned flange portion 22 thereof to provide a joint for resisting the piston effect of the resultant forces on the end wall 15. This joint is soldered or welded to prevent fluid escape and it completes the shell assembly.

In actual practice it has been found desirable to provide the inner sleeve 13 with a wall thickness greater than that necessary to resist the compressive forces in the evaporation chamber, since a certain factor of safety is required to resist the manual mishandling generally accorded to freezing chambers. The outer shell 10 may be constructed with a relatively light gage wall where saving of weight is essential, and this wall may be adequately reinforced against the tension loads by a plurality of reinforcing rings 23 formed with annular radial flanges which provide an efficient fin surface for the outer shell. As best shown in Figs. 2 and 3, the inner shell is formed with a plurality of rows of beads 24, the uppermost rows forming a mounting means for a shelf 25 and the lower rows providing a guideway for a semi-cylindrical ice tray 26.

The float chamber 16 houses a float 27 which is preferably of the bucket" type, and which is formed as a stamping having a light gage wall. This float, as will be noted in Figs. 2 and 4, occupies a major portion of the space within the float chamber, and its side walls 28 are separated from the respective end walls 15 and 12 of the shells by a relatively narrow space. The float is mounted for transverse or diametral pivotal movement in the chamber 16 by a pivotal connection formed on an inlet fitting 31 secured to the side of the chamber wall.

The fitting 31 comprises a hub portion 32 which xtends to the exterior of the evaporator through a suitable aperture formed therein, and a shoulder portion 33 which abuts the inner wall thereof. The fitting is retained against turning movement during assembly by a guide portion 34 which engages a guide bead 35 formed in the outer shell 10. The opposite side of the shoulder portion 33 is formed with integral spaced lugs 36 which receive a bracket 3'7 therebetween and which bracket is secured to the float 27. A pivot pin 38 extends horizontally through this connection and insures substantially vertical movement of the float 2'7, such movement being limited by a stop member 39 formed on the bracket 3'7 which is adapted to engage the shoulder 33.

The fltting 31 is utilized to contain a cartridge type needle valve 41 which is not claimed as novel herein. It will be sufficient for the present purposes to state that the valve 42 thereof is provided with a portion extending within the float chamber 16 and engageable by the float bracket 37 for closing movement. The hub portion 32 of the fitting 31 is internally threaded to receive an input conduit 43 leading from the condenser of the refrigerating system.

The suction line or output conduit 45 of the refrigeration system enters the float chamber 16 through an output fitting 46. This fitting is internally threaded as indicated by the numeral 47 for receiving an adjustable suction pipe extension 48 which carries a screw portion 49 at its upper extremity (Fig. 4) and which depends into the float 27.

In operation, the liquid refrigerant enters the float chamber 16 through the inlet conduit 43 and when sufiicient liquid is fed into the evaporator, the float 2'7 rises and closes the valve 42. The evaporation of the liquid refrigerant causes a recession of the liquid level. whereupon the float 27 is lowered and the valve again opened to continue the cycle. During this operation the products of evaporation are continuously Withdrawn from the evaporator through the extension pipe 48 for return to the compressor of the refrigeration system.

It has been found that by closely spacing the cylindrical walls of the shells 10 and 13, added evaporation efiiciency is obtained. For example, in one device, where the outer shell was seven inches in diameter and the spacing between the shells was approximately .070 inches, it was found that the refrigerant fllled practically the entire space, although the liquid level in the float chamher was retained at normal. Thus, by properly proportioning the shells, practically the entire wall area may be utilized for heat transference purposes (see Figs. 1 and 3). This phenomenon is apparently caused by the pressure of gas formation between the walls which forces liquid refrigerant into the upper zone above its normal level. Surface tension also aids in producing this result and in retaining the liquid in its raised position and thus the spacing between the walls must be retained at a minimum if this added efliciency is desired.

The float 27 also functions as an oil collector, since ebullition and other action in the chamber 16 introduces oil to the interior of the float in small particles to form an oil body therein which is maintained at a predetermined level by the suction pipe 48.

It is deemed advisable to protect the open bucket from violent ebullition action in the chamber 1'7, and a sheet metal baffle 50 is secured to the wall 15 to close the upper sector against communication between the chambers 16 and 1'7.

It will be obvious that the buoyancy of the float 27 will be affected by the volume of oil therein, which acts as a ballast, and, correspondingly, the buoyancy of the bucket affects the liquid level of the evaporator, since upon ballasting the bucket to its full extent, a higher liquid level will be required to float the same. The adjustable pipe 48, therefore, provides a means for varying the depth of the oil ballast in the bucket, and thus its adjustment is effective to vary the liquid level in the evaporator.

The above construction provides for rapid heat transference from the chamber 18, since its walls are in direct communication with the refrigerant within the chambers 16 and 17, and thus water placed in the ice trays therein will be rapidly frozen. This freezing action will be particularly accelerated in the lower ice tray 26 which is formed for intimate association with the wall of the chamber 18.

It is not intended that the invention be limited to the particular structure nor to the specific type of float disclosed, as it will be apparent to those skilled in the art that the principles of the invention could be incorporated in other similar structures.

I claim:

1. In a refrigeration system, an evaporator comprising a pair of elongated cylindrical shells each having an end wall, said shells being mounted in radially spaced telescoping relation to form a restricted evaporation space therebetween, the open ends of the cylinders being secured to each other to close said space, the end walls of the shells being axially spaced to provide a narrow float chamber therebetween, a float mounted for pivotal movement transversely of the float chamber, said float having spaced side walls substantially parallel to the end walls of the sleeves to provide restricted evaporation spaces between the float walls and adjacent shell walls, and inlet and outlet conduits entering between the shells, said inlet conduit having a valve connected for operation by said float.

2. In a refrigeration system, an evaporator comprising a pair of elongated cylindrical shells each having an end wall, said shells being mounted in radially spaced telescoping relation to provide a restricted evaporation space therebetween, the open ends of the shells being secured to each other to close the said space, the end walls of the shells being axially spaced to provide a narrow float chamber therebetween, a hollow float mounted for pivotal movement in the float chamber, an input conduit having a valve operated by said float to control the liquid refrigerantlevel within the evaporator, said float having its interior in communication with the space in the float chamber above the liquid level and being formed with side walls substantially parallel to the adjacent end walls of the shells to provide restricted evaporation spaces therebetween, and an outlet conduit entering said evaporator and extending into said float.

3. In a refrigeration system, an evaporator having a float chamber, a hollow float mounted .for pivotal movement in said chamber, an input conduit having a valve operated by the float to control the liquid refrigerant level in the float chamber, said float having its interior in communication with the space in said chamber above the liquid level and adapted to receive products of ebullition therefrom, including a major portion of oil, and an outlet conduit having a portion entering the chamber and having its open end extending into said float, said conduit portion being adjustable from the exterior of the chamber relative the bottom of the float to vary the volume of oil in said float, said volume of oil ballasting said float whereby adjustment of said conduit portion varies the refrigerant level in said chamber.

4. In a refrigeration system, an evaporator comprising a pair of cylindrical shells, each closed at one end and mounted in radially spaced telescoped relation with their open ends secured to each other, the end walls of the shells being spaced to provide a substantially disc shaped float chamber, a hollow float in the float chamber, a fltting secured to the inner wall of the float chamber and having a pivotal connection with said float, an input conduit connected to the fitting, valve means in said fitting communicating with said input conduit, an operating connection between said valve means and said float, and an output conduit having a portion entering the chamber at substantially the top portion thereof and depending into said float.

5. In a refrigeration system, an evaporator comprising an outer cylindrical shell having an end wall, an inner cylindrical shell having an end wall and mounted in radially spaced and telescoped relation in the outer shell to provide an evaporation chamber between the cylindrical walls, the open ends of the shells being secured to each other to seal the space therebetween, said end walls being spaced to provide a float chamber therebetween, an open float in the float chamber, inlet and outlet conduits entering the float chamber, said inlet conduit having a valve connected for operation by said float and said outlet conduit having a portion extending into'said float, and wall means closing communication between the chambers at the top of the evaporator to protect said open float from violent ebullition in the first chamber.

6. In a refrigeration system, an evaporator comprising a structure formed with a float chamber, inlet and outlet conduits entering the float chamber, float controlled valve means for the inlet conduit for maintaining a predetermined liquid level in the chamber, a pair of spaced cylindrical members forming an evaporation chamber therebetween, said evaporation chamber communicating at one end with said float chamber and being closed at the opposite end, said members being adapted to be mounted with a portion of said evaporation chamber above the liquid level in the float chamber, and the walls of said members being spaced to obtain liquid surface tension effects therebetween, whereby the liquid therebetween is maintained at a higher level than in said float chamber.

JOSEPH D. LEAR. 

